Optimal Dredge Fleet Scheduling within Environmental Work Windows: Fid-Bau Portal

Optimal Dredge Fleet Scheduling within Environmental Work Windows

C. Rainwater / H. L. Nachtmann / F. Adbesh

The U.S. Army Corps of Engineers (USACE) annually spends more than 100 million dollars on dredging hundreds of navigation projects on more than 12,000 miles of inland and intra-coastal waterways. Building on previous work with USACE, this project expands logic-based mathematical programming solution approaches to address more realistic dredge scheduling challenges faced by the USACE. In previous work, both mixed-integer and constraint programming formulations were developed to allocate dredge resources to projects system-wide while adhering to various limitations such as so-called environmental restrictions that defne when dredging cannot take place due to migration patterns of different species (e.g. turtles, birds, fish, and other wildlife). In addition, dredge equipment resource availability and varying equipment productivity rates that impact project completion times were considered. In this study we extend the previously developed constraint programming model, adding flexibility to address more of USACE's needs. The extended model allows for partial dredging during restricted periods, variable jobs sizes, multiple dredges working on a job, multiple dredging equipment trips to the same job, dredge maintenance and varying operation rates/costs. The result of our research is a more applicable decision tool that can be used by USACE to determine the appropriate dredge fleet and the optimal operations associated with that fleet for a given set of jobs and their characteristics.